This is a monthly series illustrating several characteristic moths
to look out for in our area. Text and photos by Roy Leverton.

You can also view the other months by selecting the links at the bottom of this page.

Dotted Carpet Alcis jubata

Mid July through August.

Mature woodland.

Strictly speaking, this moth is a member of the subfamily Ennominae rather than a carpet, but the name has stood for at least 150 years. Formerly scarce and local, it has increased and spread enormously in recent decades and is now found throughout our region.

Dotted Carpet requires damp sheltered woodland, where its caterpillar feeds slowly on beard lichens rather than on leaves, spending about 10 months in the larval stage. Because beard lichens require clean air, its Scottish distribution map shows few records in the more industrialised central belt.

The adult rests by day on trunks and branches, where it is well-camouflaged, particularly on birch. It may sometimes be disturbed into flight by day, but most records are from light traps.

Click on the image to enlarge it.

Juniper Pug Eupithecia pusillata

Late July into September.

Almost anywhere with juniper.

Juniper Pug overwinters as an egg, and its pupa often has a diapause of several weeks before it begins to form up. This makes it one of our last pugs to emerge, helping to simplify the identification process in this notoriously difficult group.

Where present, Juniper Pug can be abundant, as on Speyside and in the Great Glen. Even small and isolated juniper bushes growing in open moorland may produce dozens of its caterpillars when tapped over a sheet or net. The caterpillars themselves vary remarkably in both colour and markings, so that it is hard to believe they are all the same species.

As with other pugs, the adults are easily disturbed from vegetation by day, and large numbers can be attracted to light traps in suitable habitat.

Click on the image to enlarge it.

Emperor MothSaturnia pavonia

Larval stage June to September.

Mainly heather moorland.

For such a large moth, the Emperor has a caterpillar that feeds up fairly quickly. By August most are in at least their penultimate instar, though still considerably smaller than their fully grown size. They are also more intricately marked than in their final instar, with fine black freckling on a yellowish-green background, excellent camouflage amongst their foodplant. Coupled with a low density, this makes them difficult to spot in a vast sea of heather even when feeding openly by day.

However, once the Cuckoo has left, birds might not be their main enemies. Some fall victim to parasitic flies of the family Tachinidae, which presumably find them by other means than sight. Neither camouflage nor warning colouration is any defence against these. Fortunately enough caterpillars survive to produce moths the following spring.

Click on the image to enlarge it.

Plain Golden Y Autographa jota

Mid July and August.

Weedy places, gardens, roadsides.

In our area, Plain Golden Y is a widespread but rarely numerous species of lower ground that appears to be declining. It was always outnumbered about ten to one by its relative, Beautiful Golden Y A. pulchrina (see June 2009), but in the past decade it seems to have got much scarcer for no obvious reason. The proportion of pre-2000 red dots on its distribution map is noticeably higher than for others in its group.

Plain Golden Y emerges about a fortnight later than its sister species, but otherwise their life cycles and behaviour are very similar. Both rest openly on vegetation during the day, perhaps resembling a dead and crumpled leaf. At dusk they are strongly attracted to nectar flowers, having a proboscis long enough to visit honeysuckle.

Click on the image to enlarge it.

Dotted ClayXestia baja

July into September, with an early August peak.

Woodland, scrub, hedgerows, gardens.

In contrast to the previous species, Dotted Clay is thriving in Scotland but apparently undergoing a major decline in central and south-east England. Yet in Scotland it remains one of our most numerous high summer moths and if anything seems to be increasing. In 2013 my garden light trap caught 49 in one night. We can only speculate about such contrasting regional fortunes.

Like many members of its Noctuinae subfamily, Dotted Clay utilises a very wide range of foodplants and overwinters as a small caterpillar. In spring this is one of the most frequent finds by torchlight at dusk, climbing the stems of shrubs and bushes to feed on the new leaves, before descending at dawn to hide in the leaf litter.

The adult also hides by day at or near ground level, so is rarely found except by accident, for example while gardening. After dark it is a frequent visitor to nectar sources such a ragwort and garden buddleia.